A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

148 SEA WATER DISTILLATION. that is, by taking the steam from the evaporator at ordinary atmospheric pressure—no steam valve is really required with automatic working. (2) A feed cock and pipe, fitted to the upper part of the distiller casing, and leading warm water to the feed regu- lator or feed box, as the case may be. The feed cock, in case of emergency, may be used for regulating, by hand, the feed supply to the evaporator, but it is, of course, preferable to let the feed regulator or feed box do this. The feed cock is also useful for regulating, or rather mitigating, any excessive pressure that may be due to a head of water over this feed supply. Such pressure may be considerable if the apparatus is placed low down in a large ship, and might overpower the float in the feed regulator, if not controlled by the feed cock on the distiller. (3) A filling cock and pipe, fitted to the lower part of the distiller casing. This is for charging the evaporator quickly with sea water as occasion may require. (4) The dilution cock may be fitted to the same branch as the filling pipe is, in order that the same supply may be used for filling and for diluting. (5) A valve on the circulation inlet may be fitted if desired, but no valve, other than a non-return one, should be fitted on the circulation discharge pipe. (6) A relief valve is sometimes fitted on the casing, so that if any stoppage takes place in the free passage of the circulation water through the distiller, the continued action of the pump will do no injury. (7) An air pipe or vent is fitted to the upper sheaf of tubes (the condensing tubes), for allowing the excess air to escape from these tubes. This air pipe or breathing pipe can be conveniently fitted to the top of the secondary